As a way to test the drive of a display panel that includes an active matrix pixel region (e.g., a liquid crystal display panel), it is known to provide the display panel with elements for inputting test signals to the pixel region to turn on the pixels. For example, it has been disclosed that thin film transistors (TFTs) are provided between every adjacent gate lines in the pixel region to switch continuity between the adjacent gate lines from on to off, and vice versa (see Patent Document 1, for example). In this configuration, the value of a current that flows through two gate lines brought into conduction by the TFTs is measured.
The configuration described above requires a current input source and space for inserting all of the between-gate line transistors. Moreover, in order to carry out a current measurement, it is necessary to take the resistance and the current tolerance of the transistors into consideration. However, to increase the size of the pixel region in which images are displayed, it is necessary to reduce the size of the periphery of the pixel region. Therefore, it is difficult to secure space for placing the TFTs and the lines used for testing. For these reasons, it has been proposed to place terminals in the area for placing semiconductor chips (see Patent Documents 2 and 3, for example).